In certain types of applications requiring the transmission and reception of communication signals, it is convenient to utilize the conductors of an electrical power system to convey the signals. For example, co-pending application Ser. No. 189,895, filed May 3, 1989, entitled "Power Line Carrier Communication System", which is assigned to the same assignee as the present application, discloses the use of electrical power lines for monitoring refrigerated containers, caller "reefers", on board ships and in ship terminals.
It has been found that when certain types of electrical loads are energized by an electrical power line, such as solid state motor drives which chop the AC wave form, that such loads feed back electrical noise into the electrical power line, making it difficult to communicate over the power line with practical signal levels.
Since electrical noise covers a broad frequency range, it is not practical to use tuned filters, as a large number of large filters, which are difficult to tune, would be required.